Coolant flush

[benualson]

My truck has 214,000 miles on it. The coolant reservoir has a layer of brown gritty grime on it. I took off the radiator cap and found the same gritty substance. I am thinking about flushing the radiator & filling with new coolant. I cannot tell which coolant I should put in; dex-cool, or the normal green stuff...as the grit has discolored the coolant. Will I cause any harm by unscrewing the radiator petcock, flushing w/ water, and refilling? Any suggestions on coolant type? Thanks!

[Black02Silverado]

It will not hurt a thing to flush it out. You can go back with the dex-cool fluid. Might want to check your hoses while you are at it and maybe replace them. I alway mix my coolant with distilled water at a 50/50 mix.

[benualson]

if I put Dex cool in, won't there still be some old coolant in the engine block? if my current coolant is the green stuff, wouldn't it be bad if it mixed?

[Black02Silverado]

If you do a complete flush then it will not matter. You don't want to mix the two. If that is the case then go back with the green coolant. Then you will not have any issues if you happen to not completely flush out the old coolant.

[txab]

IIRC '95 was still using green. If you have green in it, I'd stick with it.

[Wolfmanjohn]

A 50/50 of Dexcool will have better heat exchange properties than a 50/50 of the green stuff. When I completely flushed all the green stuff out of my '95 Caprice LT1 cooling system sized for that green stuff and put Dexcool in there, I was in for a very pleasant surprise! That car ran cooler at 115 degrees ambient than at 60 degrees ambient!

 

By completely flush, I mean remove and clean the reservoir tank, remove the knock sensor and lower block drain plug, individually flush the heater core, replace hoses if it's time, remove and completely flush the radiator, and completely clean the cooling fins in the radiator while it's out. Only then will you realize the full benefits of a 50/50 mix of Dexcool and distilled water.

[benualson]

My auto shop in town said they can flush my cooling system with a machine that uses a chemical to clear out all the crud. He would then refill with cooland and a conditioner. This would cost $100. Sounds like a more thorough job than I could do; will it hurt anything to do this? I don't mind paying the $100.

[gmtech4]

pay it ,drain plugs on both sides have to be removed ,just the knock sensor only does one side ,,,,

 

$100 is a no brainer